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Chao CC, Lin MY, Chang CK. The Association Between Ocular Residual Astigmatism and the Efficacy of Astigmatism Correction Via Small Incision Lenticule Extraction (SMILE). Ophthalmol Ther 2023; 12:2631-2640. [PMID: 37470969 PMCID: PMC10441899 DOI: 10.1007/s40123-023-00766-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 06/26/2023] [Indexed: 07/21/2023] Open
Abstract
INTRODUCTION Astigmatism correction after small-incision lenticule extraction (SMILE) surgery is affected by several factors, including ocular residual astigmatism (ORA), which accounts for the vector difference between refractive and corneal astigmatism. Previous studies revealed the relationship between ORA and astigmatism correction after laser-assisted in situ keratomileusis (LASIK). However, in SMILE surgery, no comprehensive study exploring the link between these two variables has been performed. We have therefore assessed the association between ORA and astigmatism correction after SMILE. METHODS This was a retrospective, single-centered study. Patients with myopia or myopic astigmatism who underwent SMILE surgery using the 500-kHz Visumax laser platform and were followed up for at least 3 months were included. Patients' demographic and clinical characteristics, such as visual acuity, refractive status and corneal tomography, were recorded. ORA was calculated using Alpins Statistical System for Ophthalmic Refractive Surgery Techniques (ASSORT) Ocular Residual Astigmatism calculator. RESULTS A total of 888 eyes (408 eyes from males and 480 eyes from females) from 444 patients (mean age [standard deviation] 32.4 ± 7.1 years) were included in our study. Mean (± SD) preoperative sphere and cylinder were - 5.45 ± 1.98 (range - 10.00-0.00) diopter (D) and - 0.89 ± 0.70 (range - 4.00-0.00) D, respectively. Calculated mean ORA was 0.68 ± 0.35 (range 0.07-3.53) D. Postoperative logMAR uncorrected visual acuity was 0.03 ± 0.31. Mean postoperative sphere and cylinder were - 0.10 ± 0.56 (range - 1.5 to 1.0) D and - 0.51 ± 0.37 (- 1.5 to 0.0) D, respectively. The Pearson correlation test revealed preoperative sphere, steep keratometry (steep-K) and ORA were statistically correlated with the amplitude of astigmatism correction (P < 0.001), and the generalized estimating equations analysis showed that ORA was negatively correlated with the amplitude of astigmatism correction (P < 0.001). CONCLUSION The results of our study suggest that preoperative higher ORA may be associated with a lower magnitude of astigmatism correction after SMILE surgery in patients with all levels of astigmatism preoperative. TRIAL REGISTRATION ClinicalTrials.gov: NCT05604872. Registered 3 November 2022-Retrospectively registered. https://clinicaltrials.gov/ct2/show/NCT05604872.
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Affiliation(s)
- Chen-Cheng Chao
- Nobel Eye Institute, Taipei, Taiwan
- Department of Optometry, MacKay Junior College of Medicine, Nursing, and Management, Taipei, Taiwan
| | - Meng-Yin Lin
- Department of Ophthalmology, Shuang Ho Hospital-Taipei Medical University, New Taipei City, Taiwan
- Department of Ophthalmology, School of Medicine, Taipei Medical University, Taipei City, Taiwan
| | - Chao-Kai Chang
- Nobel Eye Institute, Taipei, Taiwan.
- Department of Optometry, Da-Yeh University, Chunghua, Taiwan.
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Pradhan KR, Arba Mosquera S. Twelve-month outcomes of a new refractive lenticular extraction procedure. JOURNAL OF OPTOMETRY 2023; 16:30-41. [PMID: 34949535 PMCID: PMC9811368 DOI: 10.1016/j.optom.2021.11.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Revised: 11/02/2021] [Accepted: 11/11/2021] [Indexed: 06/07/2023]
Abstract
BACKGROUND To evaluate the 12-month refractive and visual outcomes of Small Incision Guided Human-cornea Treatment (SmartSight®, SCHWIND eye-tech-solutions, Kleinostheim, Germany) in the treatment of myopia corrections with low to moderate astigmatism with the use of a new femtosecond laser system. METHODS 221 eyes of 114 patients consecutively treated with SmartSight lenticule extraction were assessed. The mean age of the patients was 28±6 years at the time of treatment with a mean spherical equivalent refraction of -6.26±2.17D and mean astigmatism of 0.92±0.68D. Monocular corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA) were assessed pre- and post-operatively. Refractive changes have been determined in terms of changes in refraction, as well as changes in keratometric readings. The changes in central epithelial thickness have been determined. RESULTS At twelve months post-operatively, mean UDVA was 20/21±2. Spherical equivalent showed a residual refraction of +0.48±0.31D with refractive astigmatism of 0.13±0.18D postoperatively. There was a slight decrease of -0.1 Snellen lines at 12-months follow-up. The same correction was determined using changes in refraction, as well as changes in keratometric readings. The central epithelial thickness increased by +3±2µm. Spherical equivalent correction within ±0.50D was achieved in 199 eyes (90%), and cylindrical correction in 221 (100%). Preoperative corrected distance visual acuity (CDVA) was 20/20 or better in 213 eyes (96%), and postoperative uncorrected (UDVA) was 20/20 or better in 205 eyes (93%). No eye had lost two or more Snellen lines of CDVA. CONCLUSIONS Myopic astigmatism correction with SmartSight provided good results for efficacy, safety, predictability, and visual outcomes at the twelve months of follow up. The central epithelial thickness barely increased by 3±2µm.
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Affiliation(s)
- Kishore Raj Pradhan
- Matrika Eye Center, Dhunge Dhara Marg, Ward number 9, Kathmandu 44600, Nepal.
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Han T, Fu D, Xu Y, Ding X, Chen Z, Yu Z, Zhou X. Effect of incision location on with-the-rule astigmatism correction after SMILE. Eur J Ophthalmol 2022; 33:11206721221143260. [PMID: 36464663 DOI: 10.1177/11206721221143260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
PURPOSE To explore the influence of two different incision positions of small incision lenticule extraction (SMILE) on astigmatism correction. METHODS A total of 86 eyes of 86 patients who underwent SMILE surgery were included in this retrospective study. The criteria included that the preoperative astigmatism axis to be within 165° to 180° or 5° to 15°. All eyes were divided into two groups according to the incision position. The incisions of 34 eyes were either located on the superior temporal side of the right eye or superior nasal side of the left eye (120° group), and 52 eyes were located on the superior side (90° group). Vector analysis was used to analyze pre- and postoperative 3-month astigmatism, while subgroup analysis was applied according to the preoperative astigmatism. RESULTS No significant difference of preoperative parameters was found between the two groups (P > 0.05). The efficacy and safety indexes were 1.11 ± 0.16 and 1.15 ± 0.16 in the 120° group, the numbers were 1.15 ± 0.17 and 1.16 ± 0.14 in the 90° group (P = 0.629 and P = 0.871). There was no significant difference in target-induced astigmatism (TIA), TIA axis, surgically induced astigmatism (SIA) magnitude, SIA axis, distance vision (DV) magnitude, DV axis, correction index (CI), angle of error (AofE), |AofE|, magnitude of error (MofE), index of success (IOS), or flattening index (FI) between 120° group and 90° group (P > 0.05). No significant difference was found in the subgroup analysis (P > 0.05). CONCLUSIONS The incision position has limited astigmatic effect, and the operation-induced astigmatism of SMILE surgery after 3 months was little.
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Affiliation(s)
- Tian Han
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Dan Fu
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Ye Xu
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Xuan Ding
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Zhuoyi Chen
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Zhiqiang Yu
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
| | - Xingtao Zhou
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
- NHC Key Laboratory of Myopia (Fudan University); Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
- Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
- Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, China
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Hou X, Du K, Wen D, Hu S, Hu T, Li C, Tang Y, Wu X. Early visual quality outcomes after small-incision lenticule extraction surgery for correcting high myopic astigmatism. BMC Ophthalmol 2021; 21:48. [PMID: 33468105 PMCID: PMC7816348 DOI: 10.1186/s12886-021-01807-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 01/07/2021] [Indexed: 11/16/2022] Open
Abstract
Background To evaluate early optical quality outcomes after small-incision lenticule extraction (SMILE) surgery for correcting high myopic astigmatism. Methods This retrospective study enrolled 55 eyes from 37 patients who had preoperative myopic astigmatism of ≥2.00 diopters (D) who had been treated with SMILE surgery. Preoperatively, the mean cylinder was − 2.41 ± 0.54 D (range, − 2.00 D to − 4.50 D). The preoperative and postoperative visual outcomes, refraction, and higher-order aberration (HOA) at 1 and 3 months were compared. Refractive astigmatism changes were analyzed by the Alpins vector method. Results Three months after SMILE surgery, the average cylinder was − 0.14 ± 0.31 D, and the average astigmatism vector was − 0.09 D × 6.34°. The angle of error (AofE) was limited to within ±10°, and the magnitude of error was limited to within ±1.0 D in all patients. The correction index (CI) was 0.98 ± 0.07, the index of success (IOS) was 0.08 ± 0.13, and the flattening index (FI) was 0.97 ± 0.07. Significant positive correlations were found between IOS and |AofE| (P = 0.000); negative correlations were found between FI and |AofE| (P = 0.000). The postoperative total HOA, spherical aberration, vertical coma aberration, and trefoil 30° were increased significantly compared with preoperative measurements, and the increase in HOA was closely related to preoperative astigmatism (P < 0.05). Conclusions SMILE has preferable outcomes for correcting high myopic astigmatism. Axis rotation during the surgery might influence the undercorrection of astigmatism. The increase of HOA after surgery is related to preoperative astigmatism.
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Affiliation(s)
- Xiangtao Hou
- Eye Center of Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.,Hunan Key Laboratory of Ophthalmology, Central South University, Changsha, 410008, Hunan, China
| | - Kaixuan Du
- Eye Center of Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.,Hunan Key Laboratory of Ophthalmology, Central South University, Changsha, 410008, Hunan, China
| | - Dan Wen
- Eye Center of Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.,Hunan Key Laboratory of Ophthalmology, Central South University, Changsha, 410008, Hunan, China
| | - Shengfa Hu
- Eye Center of Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.,Hunan Key Laboratory of Ophthalmology, Central South University, Changsha, 410008, Hunan, China
| | - Tu Hu
- Eye Center of Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.,Hunan Key Laboratory of Ophthalmology, Central South University, Changsha, 410008, Hunan, China
| | - Chenling Li
- Eye Center of Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.,Hunan Key Laboratory of Ophthalmology, Central South University, Changsha, 410008, Hunan, China
| | - Yanhui Tang
- Eye Center of Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.,Hunan Key Laboratory of Ophthalmology, Central South University, Changsha, 410008, Hunan, China
| | - Xiaoying Wu
- Eye Center of Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China. .,Hunan Key Laboratory of Ophthalmology, Central South University, Changsha, 410008, Hunan, China.
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Arba Mosquera S, Verma S. A review of clinical outcomes following SMILE for the treatment of astigmatism. EXPERT REVIEW OF OPHTHALMOLOGY 2020. [DOI: 10.1080/17469899.2020.1810017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Samuel Arba Mosquera
- Biomedical Engineering Office, Research and Development, SCHWIND Eye-tech-solutions GmbH, Kleinostheim, Germany
| | - Shwetabh Verma
- Biomedical Engineering Office, Research and Development, SCHWIND Eye-tech-solutions GmbH, Kleinostheim, Germany
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Small-Incision Lenticule Extraction (SMILE) for the Correction of Myopia with Astigmatism: Outcomes of the United States Food and Drug Administration Premarket Approval Clinical Trial. Ophthalmology 2020; 127:1020-1034. [PMID: 32173114 DOI: 10.1016/j.ophtha.2020.01.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 01/01/2020] [Accepted: 01/06/2020] [Indexed: 11/20/2022] Open
Abstract
PURPOSE To present outcomes of the United States Food and Drug Administration premarket approval clinical trial of small-incision lenticule extraction (SMILE) for the correction of myopia and astigmatism. DESIGN Prospective, multicenter clinical trial. PARTICIPANTS The study included 357 eyes of 357 patients treated with SMILE (50 for myopia and 307 for myopia with astigmatism). Preoperative sphere ranged between -1.00 and -10.00 diopters (D), with manifest spherical equivalent (MSE) of up to -11.50 D and refractive cylinder of up to -3.00 D. METHODS -Participants were followed up for 12 months. Corrected distance visual acuity (CDVA) and uncorrected distance visual acuity (UDVA), stability of the manifest refraction, and vector analysis of refractive cylinder are presented for the 307 eyes treated for myopia with astigmatism. Adverse events (AEs) are presented for all 357 eyes. MAIN OUTCOME MEASURES Corrected distance visual acuity, uncorrected distance visual acuity, manifest refraction, astigmatic outcomes, and adverse events. RESULTS Of the 307 astigmatic eyes enrolled in the study, 304 were treated successfully. In 3 eyes, the procedure was aborted because of intraoperative suction loss. The mean MSE reduced from -5.39±2.30 D at baseline to -0.01±0.24 D at 12 months. Of all eyes, 95.3% were within 0.50 D of emmetropia at 12 months. The percentage of eyes with UDVA of 20/20 or better was 89.0%. No loss of 2 or more lines of CDVA was observed at the 12-month visit. The refractive cylinder reduced from -1.53±0.70 D at baseline to -0.18±0.31 D at 12 months. The mean correction ratio of refractive cylinder was 0.96±0.16 and a slight undercorrection was apparent for higher attempted corrections of astigmatism. Three intraoperative AEs associated with difficult lenticule removal and resultant cap tear occurred, and all resolved without sequelae at postoperative day 1. During the postoperative period, 8 AEs were recorded, but none of them had significant consequences. CONCLUSIONS Small-incision lenticule extraction for the treatment of myopia and astigmatism was safe and effective, and the reported AEs had no significant impact on visual acuity. Slight undercorrection of refractive cylinder requires further attention.
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Chow SS, Chow LL, Lee CZ, Chan TC. Astigmatism Correction Using SMILE. Asia Pac J Ophthalmol (Phila) 2019; 8:391-396. [PMID: 31490198 PMCID: PMC6784860 DOI: 10.1097/01.apo.0000580140.74826.f5] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 06/17/2019] [Indexed: 11/26/2022] Open
Abstract
Small incision lenticule extraction (SMILE) was introduced in the recent decade for the treatment of myopia and myopic astigmatism. This flap-free technique has a high efficacy and safety profile and also carries potential advantages over laser in situ keratomileusis such as a better corneal biomechanical stability, reduction in dry eyes rate, and the avoidance of flap complications. However, there have been concerns regarding the precision of astigmatism correction that undercorrection has been reported to be apparent. Various factors that affect astigmatism correction have been identified in the literature. The purpose of this review is to discuss the factors that affect astigmatism correction in SMILE and several techniques to improve the refractive outcomes.
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Affiliation(s)
- Sharon S.W. Chow
- Department of Ophthalmology, Grantham Hospital, Hong Kong, China
| | | | - Chester Z. Lee
- Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Tommy C.Y. Chan
- Department of Ophthalmology, Hong Kong Sanatorium & Hospital, Hong Kong, China
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
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Damgaard IB, Ivarsen A, Hjortdal J. Intrastromal Lenticule Rotation for Treatment of Astigmatism Up to 10.00 Diopters Ex Vivo in Human Corneas. J Refract Surg 2019; 35:451-458. [PMID: 31298725 DOI: 10.3928/1081597x-20190618-02] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 06/18/2019] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate the feasibility of intrastromal lenticule rotation (ISLR) as a novel technique for management of astigmatism up to 10.00 diopters (D). METHODS Eighteen human donor corneas were mounted on an artificial anterior chamber. After laser application and dissection, the lenticule was rotated 90° in the intrastromal pocket. Scheimpflug tomography (Pentacam HR; Oculus Optikgeräte GmbH, Wetzlar, Germany) was acquired preoperatively and following ISLR. The attempted astigmatic correction was twice the cylindrical magnitude of the lenticule referenced to the corneal plane: 4.80 D (5.00 D group, n = 9) and 9.32 D (10.00 D group, n = 9), respectively. The change in keratometric astigmatism was evaluated by vector analysis. RESULTS In the 5.00 D group, ISLR caused a mean absolute surgical induced astigmatism (SIA) of 5.30 ± 1.14 D with a correction index (CI) of 1.14 ± 0.25 and an angle of error (AoE) of -0.80° ± 4.61°. In the 10.00 D group, the SIA averaged 9.57 ± 1.10 D with a CI of 1.03 ± 0.12 and an AoE of 2.75° ± 3.60°. The average total corneal refractive power (TCRP) increased 1.36 ± 0.67 and 1.95 ± 1.57 D in the 5.00 D and 10.00 D groups, respectively. Postoperative optical coherence tomography revealed stromal redistribution in the periphery of the optical zone with tissue addition in the preoperative steep meridian and tissue reduction in the preoperative flat meridian. CONCLUSIONS ISLR seemed feasible and precise for management of regular astigmatism up to 10.00 D ex vivo in human donor corneas. A myopic shift was observed in TCRP. The in vivo corneal remodeling after ISLR warrants investigation. [J Refract Surg. 2019;35(7):451-458.].
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Yildiz BK, Urdem U, Goksel Ulas M, Yildirim Y, Agca A, Fazil K, Aygit ED, Taskapili M, Demirok A. Correction of myopic astigmatism by small incision lenticule extraction: does laterality matter? Lasers Med Sci 2018; 34:311-316. [DOI: 10.1007/s10103-018-2591-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 07/13/2018] [Indexed: 12/01/2022]
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Ng ALK, Cheng GPM, Woo VCP, Jhanji V, Chan TCY. Comparing a new hydroexpression technique with conventional forceps method for SMILE lenticule removal. Br J Ophthalmol 2017; 102:1122-1126. [PMID: 29122820 DOI: 10.1136/bjophthalmol-2017-310993] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 10/22/2017] [Accepted: 10/24/2017] [Indexed: 12/30/2022]
Abstract
BACKGROUND We described a modified 'hydroexpression' technique for the lenticule removal during small-incision lenticule extraction (SMILE) surgery and compared the results with conventional forceps method. METHODS This was a retrospective, comparative study of 50 patients who underwent SMILE surgery by the same surgeon. We compared the 1-week and 3-months postoperative results after SMILE using the hydroexpression technique with the conventional forceps technique. Main outcome measures included uncorrected distance visual acuity, corrected distance visual acuity, refractive accuracy, safety index and efficacy index. RESULTS The baseline characteristics were comparable between both groups. At postoperative 1 week, the safety index in forceps and hydroexpression group was 0.93±0.11 and 0.97±0.10, respectively (P=0.246). At 3 months, they were 1.00±0.06 and 0.99±0.09 (P=0.850). For efficacy indices, at 1 week they were 0.84±0.17 and 0.91±0.17 (P=0.158). At 3 months, they were 0.92±0.13 and 0.94±0.19 (P=0.624). All eyes aimed for a plano target. 96% in forceps group and 90% in hydroexpression group were within ±0.50 dioptre (D) in spherical equivalent refraction (SEQ) correction at postoperative 3 months (P=0.567). The mean errors of SEQ correction were -0.10±0.21 D in forceps group and -0.08±0.30 D in hydroexpression group (P=0.705). CONCLUSION Hydroexpression was simple and safe and had early results comparable to the conventional forceps technique. This technique was particularly useful for cases with more adhesions between lenticule and anterior cap, thin lenticule cases and for the inexperienced SMILE surgeons.
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Affiliation(s)
- Alex L K Ng
- Department of Ophthalmology, The University of Hong Kong, Cyberport, Hong Kong
| | | | | | - Vishal Jhanji
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Philadelphia, USA.,Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Kowloon, Hong Kong
| | - Tommy C Y Chan
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Kowloon, Hong Kong
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